ls = train_data(:,1);
uls = unique(ls);
uls_num = histc(ls,uls);
% str1 = '= train_data(ls==uls_num(i),:);';
% str0 = 'train';
% for i = 1:length(uls)
%     eval([str0,num2str(uls(i)),str1]);
% end